In recent years, infrared (IR) optical gas imaging (OGI) cameras have been tools extensively used for gas leakage detection and monitoring due to better visualization of gas leaks, reduced inspection time, and improved safety as compared to conventional gas sensing techniques, such as catalytic detectors.
In addition to the practical qualitative use of IR OGI cameras, quantitative use has been suggested. For example, it is possible to quantify a gas concentration-length (a concentration integrated along a path length, e.g., in units of parts per million-meter, or ppm·m) of an imaged plume with appropriate calibration. The gas concentration-length may also be referred to as a gas concentration path length (CPL).
IR OGI is one of two methods recognized by the U.S. Environmental Protection Agency (EPA) for gas Leak Detection and Repair (LDAR) surveys in the U.S. oil and gas industry, the second being EPA Method 21.